Froth-flotation process



Patented Sept. 4, 1934 FROTH-FLQTATION PROCESS Mahlin S. Hansen, Indianapolis, Ind., assignor to Peter C. Reilly, Indianapolis, Ind.

' No Drawing. Application August19, 1932, Serial No. 629,423 g 10 Claims. (01109 -166) 3 This invention relates to improvements in the concentration of minerals of oxidized ores by the froth-flotation process. More particularly, the invention aims-to improve the efficiency of the froth-flotation process as applied to oxidized ores, by the use of certain modifying agents which have the double effect of activating the desired oxidized minerals so that they are made more amenable to froth-flotation and of dispersing slimes.

Certain minerals have not heretofore been readily amenable to the froth-flotation process, and have required relatively large quantities of the selector reagents to effect their flotation. An important class of these is the oxidized minerals which are present in oxidized ores; and it is to these that my present invention is directed. By oxidized ores I mean those ores which are commonly so known to' miners and millmen; and which may be partly or wholly true carbonates,

but are often partly or largely sulfates, hydroxides, oxides, and analogous compounds, and are usually quite complex. Among the minerals which may be included in the term oxidized minerals may be mentioned phosphate rock, fluorspa'r, phosphate, talc, barite, calcite, feldspar, garnet, hematite, manganocalcite, malachite, pyrolusite, rhodochrosite, scheelite, and Wolframite. Because of the relatively low unit valueof the minerals of this group, andbecause of the relatively high quantity of selector reagents heretofore necessary to effect flotation, the application of the froth-flotation process to their concentration has been in general uneconomical.

Further, with most ores, including those containing oxidized minerals, the presence of slimes in the pulp has been a serious impediment to the successful concentration of the mineral values by the froth-flotation process, and in many cases the presence of slimes has in itself prevented the concentration of mineral even when the mineral was otherwise readily amenable to flotation.

This invention is based upon the discovery that in the application of the froth-flotation process to the flotation of oxidized-minerals in oxidized ore pulps, the use in regulated small quantities of a fluosilicate of the class including copper fluosilicate (such as CuSiFsBHaO), silver fluosilicate (such as AgzSiFoAJ-IzO), zinc fluosilicate (such as-ZnSiFmHzO), cadmium fluosilicate (such as CdSiFs.6H20), mercury fluosilicate. (such as HgSiFaHzO), and lead fluosilicate (such as PbSiFs.6H2O and PbSiFs.4H20) markedly aids in effecting selection of valuable mineral from gangue. The use of one or more of these fluosilicate compounds makesit possible to apply thefroth-flotation process in the concentration of oxidized minerals at greatly reduced cost, and in some cases where it has not heretofore been commercially practical.

The following advantages are obtained by the use of the aforesaid modifying agents:

(l) 'A decrease is made in the amount of selector reagents required to effect flotation.

(2) A dispersion of slime from both the mineral surfaces and the froth surfaces is accomplished; which obviates the deleterious effect of slimes. j v

(3) In general, a more brittle froth is obtained,

which permits greater selectivity in the difierential or preferential flotation of minerals.

One hypothesis as to the activating action in the flotation circuit by. the fluo'silicates of metals of the class comprising copper, silver, zinc, cad- -mium, mercury, and lead, is as follows:

The cations of these salts in solution exchange for cations on the mineral surface, thereby producing a surface which is more amenable to the froth-flotation process and more readily affected by selector flotation reagents. In addition to this cation effect, the slimes-dispersion which I obtain both from the mineral surfaces and from the froth surfaces is due to the highly effective action of the anions.of such fluosilicates in solution. The slime-freed mineral surfaces are clean and unobstructed surfaces for the action of the selector flotation reagents, which makes for greater efliciency and economy. The effect of freeing the froth of slimes is to provide clean, unloaded froth surfaces for buoying the mineral particles to be floated.

Examples of the use of these fluosilicates are given below. Example I shows the use of lead fluosilicate and of zinc fluosilicate in the flotation of an "oxidized copper mineral inan ore pulp containing both sands and slimes, in an acid circuit. Example II shows the use of lead fluosilicate and of cupric fluosilicate in the flotation of the non-metallic mineral feldspar, in an ore pulp substantially free from slimes, in a'neutral circuit. Example III shows the use of zinc fluosilicate in the flotation of an oxidized lead mineral, in an ore pulp containing both sands and slimes, in an alkaline circuit. In these examples the flotation reagents used in conjunction with the fluosilicates are given merely by way of example, since any suitable flotation reagents (comprising both froth and selector reagents) may be employed.

Example I Data of Example I Percent re- PbSlFaGHzO ZnS1Fu.6H:O Test covery of lbs. per ton lbs. per ton copper None. None. 0.0

0. 25 None. 42. 0

0. 50 None. 65. 0

None. 0. 25 50. 0

None 0. 50 78.0

Example II The following tests were run on pure orthoclase feldspar mineral (minus 100 plus 320 mesh) using fifty-gram charges in a Gates-Jacobson flotation cell with amounts of suitable frother and selector reagents, such as pine oil and amyl dithidphospho-oleic acid, equivalent to 0.20 lb. and 0.75 lb. respectively per ton of mineral, together with such quantities of fluosilicates as activating reagents as are shown below, in quantities equivalent to pounds per ton of mineral as indicated. The hydrogen ion value of the pulp was maintained at pH 7.0.

Data of Example II PbSiF fiHgO ousirtemo Percent Test recovery of lbs. per ton lbs. per ton mineral None. None. 0. 0 l. 0 None. 20. 0 1. 5 None. 31. 0 None. 1. 0 78. 0 None 1. 5 88. 0

Example III The following tests were made on an oxidized ore of lead. The important characteristics of the ore were as follows:

(1) The ore was high-grade, containing a relatively large amount of lead associated with silver, zinc, and iron;

(2) All of the silver was associated with the 60 lead minerals;

(3) Crushing to 120-mesh was necessary to entirely unlock the economic minerals;

(4) The gangue was decomposed, giving rise to much clay, and contained a large proportion of limestone;

(5) Soluble salts were present which had a marked coagulating effect; (6) 36% of the lead was present as oxidized lead minerals.

The ore was crushed dry to 28-mesh by jaw crushers, followed by wet grinding in a porcelain ball-mill with flint pebbles, to 120-m'esh. This product was run over a 12 by 30 inch Wilfley gravity concentrating table, obtaining a ,relatively coarse lead concentrate containing 20.44%

of the lead content of the ore. The table tailing comprising the oxidized portion of the ore was thickened'to a pulp dilution of 4 to 1, and was used for feed in the flotation tests of the following table.

The flotation tests were made with a 5.00-gram Janney flotation testing machine.

-Amounts of suitable sulfidizer, frother, and selector reagents, such as sodium sulfide, pine oil, and sodium xanthate, equivalent to 4.5 lbs., 0.20 lb., and 0.35 lb. respectively per ton of ore, were added in the order named; together with zinc fluosilicate as an activator reagent, added in order between the sulfidizer and the frother, in amounts equivalent to pounds per ton of ore as indicated. In the flotation feed, the assay was 12.0% lead, 3.0% zinc and 10.8% iron. The hydrogen ion concentration of the pulp circuit was pH 8.4.

Although I have given specific examples to illustrate my invention, they are illustrative only. Variations in the quantities of reagents employed, the combinations of reagents, the kinds of oxidized-ores", the hydrogenion value of the pulp, and the steps of the procedure, may be varied in practice as determined by the composition of the given oxidized-ore without departing from the invention claimed. For instance, the treatment of the oxidized-ore pulp with the fluosilicate or fluosilicates may be by adding the latter to the ore prior to the actual formation of the pulp; and the term treating the ore pulp as used in the claims is intended to include that as well as a treatment after the oxidized-ore pulp has been formed.

I have found that the fluosilicates can be used in the crude form as well as in the relatively pure form. The fluosilicate used may be in solid or liquid form, or it may be dissolved in water or other solvent. A plurality of fluosilicates may be used together. I have also found it advantageous at times to form the desired fluosilicate directly in the ore pulp, as for example by the interaction of a fine suspension of cupric hydroxide and a solution of hydrofiuosilicic acid, or by a. solution of sodium fluosilicate and copper sulphate. Other methods of producing these fluosilicates in the flotation circuit will occur to those skilled in the art.

With some oxidized ores it is advantageous to heat the pulp to a temperature of about 90 F. to 130 F.

These fluosilicates can be used with desirable and effective results in alkaline, neutral, or acid cadmium fluosilicate, mercury fluosilicate, and lead fluosilicate to activate the oxidized minerals; and subjecting the treated oxidized-ore pulp to the froth-flotation process in the presence of a selector reagent.

2. The process of concentrating oxidized minerals from oxidized ores by froth flotation, comprising treating an oxidized-ore pulp with a fluosilicate of the class consisting of copper fluosilicate, silver fluosilicate, zinc fluosilicate, cadmium fluosilicate, mercury fluosilicate, and lead fiuosilicate to activate the oxidized minerals; and subjecting the treated oxidized-ore pulp to the froth-flotation process in an acid circuit in the presence of a selector reagent.

3. The process of concentrating oxidized minerals from oxidized ores by froth flotation, comprising treating an oxidized-ore pulp with a fluosilicate of the class consisting of copper flu'osilicate, silver fluosilicate, zinc fluosilicate, cadmium fluosilicate,- mercury fluosilicate, and lead fluosilicate to activate the oxidized minerals; and subjecting the treated oxidized-ore pulp to the froth-flotation process in a neutral circuit in the presence of a selector reagent.

4. The process of concentrating oxidized minerals from oxidized ores by froth flotation, comprising treating an oxidized-ore pulpwith a fiuosilicate of the class consisting of copper fluosilicate, silver fluosilicate, zinc fluosilicate, cadmium fluosilicate, mercury fluosilicate, and lead fiuosilicate to activate the oxidized minerals; and subjecting the treated oxidized-ore pulp to the froth-flotation process in an alkaline circuit in the presence of a selector reagent.

5. The process of concentrating oxidized minerals from oxidized ores" by froth flotation, comprising treating an oxidized-ore pulp with a fluosilicate of the class consisting of copper'fluosilicate, silver fluosilicate, zinc fluosilicate, cadmium fluosilicate, mercury fluosilicate, and lead fluosilicate to activatethe oxidized minerals; and subjecting the treated oxidized-ore pulp to the froth-flotation process with frother and selector reagents.

6. The process of concentrating feldspar minerals by froth flotation of pulps of oxidized ores containing such feldspar minerals, comprising treating the pulp of such oxidized ore with a fluosilicate of the class consisting of copper fluosilicate, silver fluosilicate, zinc fluosilicate, cadmium fluosilicate, mercury fluosilicate, and lead fluosilicate to activate the feldspar minerals; and subjecting such treated oxidized-ore pulp to the froth-flotation process in the presence of a selector reagent.

'7. The process of concentrating minerals from oxidized ores by froth flotation, comprising treating an oxidized-ore pulp with copper fluosilicate to activate the oxidized minerals; and subjecting the treated oxidized-ore pulp to the froth-flotation process in the presence of a selector reagent.

8. The process of concentrating minerals from oxidized ores by froth flotation, comprising treating the oxidized-ore pulp with zincfluosilicate to activate the oxidized minerals; and subjecting the treated oxidized-ore pulp to the: froth-flotation process in the presence of a selector reagent.

. I 9. The process of concentrating rmnerals from oxidized ores by froth flotation, comprising treating the oxidized-ore pulp with lead fluosilicate to activate the oxidized minerals; and subjecting the treated oxidized-ore pulp to the froth flotation process in the presence of a selector reagent.

10. The step in the froth-flotation process of oxidized-ore concentration, comprising treating an oxidized-ore pulp with a fluosilicate of the class consisting of copper fluosilicate, silver fluosilicate, zinc fluosilicate, cadmium fluosilicate, mercury fluosilicate, and lead fluosilicate to activate the oxidized minerals, in the presence of a selector reagent.

MAI-ILIN S. HANSEN. 

